Bad service received

good day, I took my vehicle for a 75000 service to Mcduling vw booysens I got a call advising me if I would like to do the front brakes , which I refused due to financial constraints , I received my vehicle but when my vehicle was washed the cap on the right hand side on the wheel cap was not replaced , when I called the service consultant she advised she needs to check the job card as they did not touch the wheels how did the cap go missing , im very disappointed and annoyed at the service received.